Spectrally Concentrated Error-Correcting Codes for Low-Power Decoding

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Solution Overview

Problem

Conventional error-correcting codes, such as McEliece systems, are impractical for small devices with low power due to high computing resource requirements for decoding and encoding, especially when compared to popular algorithms like low density parity check codes and Turbo codes.

Innovation Solution

The development of a low dimensional spectral concentration (LDSC) code that can be encoded and decoded using standard computer arithmetic, reducing processing energy consumption, and allowing list-decoding on low-power devices by applying a special randomized Fourier transform to generate a list of message candidates rather than codewords.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional error-correcting codes (McEliece systems) are used to achieve high error correction capability, then the percentage of correctable errors is improved, but the computing resource requirements and power consumption increase significantly

Engineering Contradiction:
Improveerror correction capabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent transforms the decoding problem from the Hamming space to the Fourier domain by applying a randomized Fourier transform. This parameter change in the computational domain allows low-power devices to efficiently compute correlations and identify error patterns that would otherwise require extensive computational resources in the time domain.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the traditional iterative decoding algorithms (which require complex logical operations and multiple passes) with a direct Fourier-based approach. This substitution uses spectral analysis to directly identify error locations and magnitudes, reducing the mechanical complexity of the decoding process and enabling implementation on resource-constrained devices.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If list-decoding is applied to correct high levels of noise errors, then the noise tolerance is improved, but the processing complexity and computational load increase

Engineering Contradiction:
Improvenoise toleranceVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent moves the decoding operation from the one-dimensional Hamming space to the multi-dimensional Fourier spectrum. By analyzing the error patterns in the frequency domain across multiple spectral components, the system can identify and correct multiple errors more efficiently than traditional single-domain approaches, reducing the apparent complexity of list-decoding.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The randomized Fourier transform acts as an intermediary that converts the complex error correction problem into a simpler spectral analysis problem. This intermediary transformation enables the use of efficient Fast Fourier Transform algorithms and simplifies the identification of error patterns, making high-level noise correction feasible on low-power devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Use of energy by moving object

If spectrally concentrated codes are used to reduce processing requirements, then the power consumption is reduced, but the code design complexity increases

Engineering Contradiction:
Improveprocessing powerVSAvoidcode design complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent performs preliminary encoding that embeds spectral concentration properties into the code structure. By pre-organizing the code words to have concentrated spectral energy, the decoding process on low-power devices can exploit this structure to reduce computational requirements, while the complexity is shifted to the encoding stage which can be performed on more capable systems.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables efficient error correction on low-power devices, such as smart cards and handheld computers, by reducing processing power requirements and allowing correction of a high percentage of noise errors, even in high noise levels, while maintaining security through spectrally concentrated codes.

Implementation Method 1

applying a special randomized Fourier transform to generate a list of message candidates rather than codewords

Methodology Applied
Scientific EffectFourier transform:

Data Source

PatentUS7941726B2Low dimensional spectral concentration codes and direct list decoding
Publication Date: 2011.05.10 MICROSOFT TECHNOLOGY LICENSING LLC
  • US7941726B2 patent drawing
  • US7941726B2 patent drawing
  • US7941726B2 patent drawing

AI summary

Systems and methods provide an optionally keyed error-correcting code that is spectrally concentrated. Each codeword of the low dimensional spectral concentration code (LDSC code) typically has very few coefficients of large magnitude and can be constructed even with limited processing resources. Decoding can be performed on low power devices. Error-correcting code is constructed around a key using basic computer arithmetic for computations instead of finite field arithmetic, thus saving energy. A recipient who possesses the key enjoys correction of a relatively high percentage of noise errors. In one implementation, a direct list-decoder iteratively estimates a list of message words directly, instead of a list of codewords. In variations, a unique message word is selected from the list either by applying a randomness test or by using message passing.